It is a well-known fact that in many parts of the world, safe, clean water can only be obtained by using techniques which are aimed at purifying water. One of the known techniques is exposing water to ultraviolet light, which has a disinfecting effect on the water. In general, household devices for subjecting water to a treatment with ultraviolet light are known, wherein these devices may be stand-alone devices or part of a larger assembly in which more water purifying treatments are carried out during operation. An example of a larger assembly is an assembly comprising various modules, comprising a module having a reverse osmosis filter besides a module having a source for emitting ultraviolet light.
When ultraviolet light is used for treating water, it is important that all portions of a quantity of the water are exposed to the light for a certain period of time. If the time is too short, too many active microbes remain in the water, and the desired result of the treatment is not obtained. One way of guaranteeing an effective treatment of the water is arranging the source for emitting ultraviolet light in a relatively small container, and letting a quantity of water stay in that container for an appropriate length of time.
However, there is a disadvantage that is related to using a relatively small container, namely the fact that only small quantities of water can be treated at one time. A larger container would require a more powerful source for emitting ultraviolet light and/or more sources for emitting ultraviolet light, which is not an option in applications in countries where not only safe water is scarce, but electric current is scarce as well.